The preferred embodiments of the present invention generally relate to electrical connectors for use with high speed serial data, and more particularly, to connector assemblies for transferring high speed serial data from a cable to a circuit board.
In the past, electrical cable assemblies have been proposed for connecting electrical cable to circuit boards. Conventional cable assemblies have been provided with an equalizer circuit board within the connector for performing signal conditioning. Performing signal conditioning within a circuit in the connector assembly, reduces the time required to incorporate signal conditioning circuit elements with a cable assembly and reduces the time required for connection of the circuit elements with the electrical contacts and the cable conductors. One example of a conventional cable assembly with an equalizer board is described in U.S. Pat. No. 5,766,027, commonly owned with the present application.
Conventional high speed serial data connectors (HSSDC) comprise a plug and receptacle combination interconnected through contact fingers. The plug receives an insulated holder that, in turn, receives an equalizer card. The equalizer card includes signal conditioning circuitry.
HSSDC connectors form a grounding plane surrounding the adjoining surfaces of the receptacle and plug in order to afford electromagnetic interference (EMI) shielding around the contact fingers forming the high speed serial data connection between the plug and receptacle. In conventional HSSDC connectors, the grounding plane has been maintained by locating a plurality of grounding beams on the top, bottom and side walls of the receptacle and engaging the top, bottom and side surfaces of the plug. Conventional grounding beams are J-shaped integral extensions of the walls and are bent to project forward, upward and into the opening of the receptacle. The J-shaped ground beams are biased inward to maintain an electrical connection with the plug once inserted.
However, J-shaped grounding beams take up an operation region inside the receptacle between the receptacle and plug walls. The region thickness substantially equals the radius of the J-shaped portion of the grounding beam. Consequently, the height and width of the opening in the receptacle must be greater than the height and width of the plug by an amount at least equal to the curved radius of the grounding beams. When grounding beams are located above, below and on either side of the plug, they undesirably increase the height and width of the receptacle. Certain applications for HSSDC connectors have significant space constraints.
In addition, the distance between the grounding beams should be maintained less than a predetermined maximum spacing. Otherwise, energy due to high speed signals radiates from the connection of the plug and receptacle. The spacing between grounding beams controls the frequency range at which signals may be carried through the connection. As the frequency of the transmitted signal increases, the maximum acceptable distance between the grounding beams decreases. The maximum distance is calculated between the two grounding beams that are furthest from one another (e.g., top to bottom, side to side, top to side or side to bottom). The connector assembly is preferably operable with frequencies having a wavelength range between six and twenty-four times greater than the largest distance between any two grounding beams.
The need for a large portion of the perimeter to be covered with grounding contacts is balanced with other design considerations, such as physical constraints, material cost, complexity and the forces needed to connect the plug and receptacle. As additional grounding beams or contacts are added, the plug becomes harder to insert into the receptacle since each contact presents a contact force to the plug that must be overcome to bend the contact open. A compromise is reached between the cost, complexity, physical size, forces needed to insert the plug and the EMI shielding characteristics of the connector.
Conventional HSSDC assemblies have used sheet metal to construct the plug and receptacle. Sheet metal is folded into a desired configuration. When protrusions, shelves and other features are desired to be added to the plug, holes must be punched through the sheet metal shell, or separate components must be fitted in the sheet metal to offer the features. Components, separate and apart from the metal shell, are also provided to latch the plug in the receptacle. It is undesirable to punch holes through the metal shell since the openings permit leakage of electromagnetic radiation. Conventional HSSDC connectors provide a plastic insert into the plug metal shell. The plastic insert includes the desired features for holding the PC equalizing board.
A need exists for an improved HSSDC connection assembly that simplifies the number of parts needed to construct the connector and reduces the physical dimensions of the connector without sacrificing electrical performance, latching performance or connection forces. It is an object of the preferred embodiments of the present invention to meet one or more of these needs and other objectives that will become apparent from the description and drawings set forth below.
A connector assembly is provided having upper and lower shells. The upper shell includes a top, sides, a front face and a back wall, while the lower shell includes sides, a bottom, a front wall and rear wall. The sides of the lower shell include recesses formed in edges thereof. Flanges are provided on the sides of the upper shell. The flanges have tabs extending downward therefrom that are received in the recesses in the edges of the sides of the lower shell when the upper and lower shells are joined. The recesses hold the flanges against the sides of the upper shell. The recesses may be slotted.
In at least one embodiment, the front face of one of the upper and lower shells is provided with at least one pin, while the front face of the other of the upper and lower shells is provided with a crossbar. The pin is inserted under the crossbar to securely retain the front faces of the upper and lower shells joined with one another.
Optionally, a skirt may be formed on at least one of the edges of the sides of the upper and lower shells. The skirt forms a sealed connection between the sides of the upper and lower shells.
Optionally, a latch assembly may be mounted to the upper shell. The latch assembly includes flanges formed integral therewith that snappably engage the sides of the upper shell. The latch assembly may also include a lead section with a hole therein that is secured over a knob formed on the front face of one of the upper and lower shells. The pin and crossbar combination cooperate to retain the lead section of the latch assembly.